Bench testing rally gauges

-
4spdragtop

4spdragtop

FABO Gold Member
FABO Gold Member
Joined
Aug 28, 2009
Messages
41,621
Reaction score
25,550
Location
Ontario Parts Unknown
I know the fuel gauge has ivr in it, I'm trying to see if that gauge and temp gauge is toast. I'm not looking to calibrate, simply looking for needle deflection. I'm using 6v lantern battery, red/positive to "I" post, but should the -ve be hooked to sender/"S" or the "A"?
Pics attached, the 3 post is fuel obviously, the 2 post is temperature.
Thanks
Steve

20200215_153118.jpg


20200215_153145.jpg


20200215_153208.jpg


20200215_153224.jpg
 
6 is way too much, Steve. I had an old post I think 3V? Polarity does not matter........Standby........LOL

.............and I can't find that old thread!!
 
Last edited:
My money is voltage acrossed A and I

You should also have low numerical resistance between A and I (about 10 to 13 ohms. I just tried a 1.5v AA battery an it made the fuel guage read E with 0.12A
 
I was just about to try the same test. My understanding is that the instruments are 5V. I was going to use a model railroad power supply with a rheostat.
 
as long as you do not apply more than ~5 v you should be OK
 
It is absolutely possible to bench test. It took me forever to figure out how but after I got it, I built my own tester.

I made it so you can test the gauge by itself or test fuel gauge with an actual fuel sender in the circuit

CIMG0053.JPG


CIMG0054.JPG


CIMG0055.JPG


CIMG0056.JPG
 
I used a 12 volt power supply and then I put a voltage regulator off a parts cluster inline to simulate it being in the car or you can leave the gauge in the cluster and test through there, using the voltage regulator in place already

CIMG0063.JPG
 
4spdragtop said:
I know the fuel gauge has ivr in it, I'm trying to see if that gauge and temp gauge is toast. I'm not looking to calibrate, simply looking for needle deflection. I'm using 6v lantern battery, red/positive to "I" post, but should the -ve be hooked to sender/"S" or the "A"?
Pics attached, the 3 post is fuel obviously, the 2 post is temperature.
Thanks
Steve

View attachment 1715470753

View attachment 1715470754

View attachment 1715470755

View attachment 1715470756
Click to expand...

Take a peak behind. If you see black nichrome winding not good! The nichrome should be nice and white colored or slight brownish. For me my fuel gauge looked very nice but temp and oil were toasty black! Thus the new gauges from Charger Specialties. Sometimes the regulator and fuel gauge look decent but! Surely some experts will reply in short order! My Opinion is replace with the modern and upgrade the VR. I will catch rath for this but JMO! I am a happy camper with factory look gauges that work!
 
Last edited:
Steve if you can post a photo of how it sits in the board, with a photo of the board traces I can tell you. I THINK the I is "ignition" and S of course is sender. That would leave A the output of the regulator to jumper over to the other gauges.
 
Thanks all, heres pics with fuel and temp gauges sitting in a circuit board. I wrote on the board which posts were "I" and which were "S".
Thanks everyone for the help.

20200215_222149.jpg
 
Geez I wuz headed to bed, but saw this. Instrument panel is now moved to the top of the 'to do' list.
Here's the cheat sheet I was working on in preparation for this.
upload_2020-2-15_23-3-15.png


Acc Power comes from the welded splice in the Accessory feed.
Fuel Connects to the fuel sender in tank.
5 Volts is the IVR feed to the other gages.
Temp Connects to Temperature sender on engine
Oil Connects to the Oil Pressure sender on engine.

Check the colors and positions of the wires on the multi-connector.
Too risky to just go by the diagrams without checking.

Black should come from the accessory circuit.
Everything in this post is referencing 1967.
 
Last edited:
4spdragtop said:
So to test fuel, put -ve to "A" and +ve to "I" I'm assuming?
Click to expand...
See what the others say. I don't think you can drive the fuel sender backwards through the IVR.
It looks to me like you can put 6 Volts + on Fuel gage I, with fuel gage S connected to a resistor or a spare fuel sender.
6 Volt negative connects to the other side of the resistor or the fuel sender body.

Was there capacitor on the IVR output stud or anywhere?
 
Ivr should be inside fuel gauge. I have tested fuel before with a 6v battery, I should have written it down dammit.
Mattax said:
See what the others say. I don't think you can drive the fuel sender backwards through the IVR.
It looks to me like you can put 6 Volts + on Fuel gage I, with fuel gage S connected to a resistor or a spare fuel sender.
6 Volt negative connects to the other side of the resistor or the fuel sender body.

Was there capacitor on the IVR output stud or anywhere?
Click to expand...
 
Mattax said:
Was there capacitor on the IVR output stud or anywhere?
Click to expand...
I ask because I saved this photo from the internet - maybe FABO.
upload_2020-2-15_23-36-46.png


But don't see any reference to one in the books or you photos.
 
4spdragtop said:
Ivr should be inside fuel gauge. I have tested fuel before with a 6v battery, I should have written it down dammit.
Click to expand...
I'm just going by how its normally hooked up.
I've read the IVR works by switching on and off very quickly. That's why I don't know if putting power on the IVR can be done safely or to any good effect. The cap makes sense in that it could help make the output smoother, but again others will know alot more.

Going by your photos and the shop diagram, this is what I see. If there's another way to test, I again defer to others with the knowledge and experience. I wouldn't put power through without some device to provide resistance. Is the minimum on the fuel sender zero? or something a bit above that? Hate to see a gage burned by over current.
upload_2020-2-15_23-48-12.png
 
4spdragtop said:
Thanks all, heres pics with fuel and temp gauges sitting in a circuit board. I wrote on the board which posts were "I" and which were "S".
Thanks everyone for the help.

View attachment 1715471067
Click to expand...

OK what I told you is correct. The I is 12V from the key, S is to sender. The black cap is the jumper, that is the output of the regulator which jumpers over to the other two gauges
 
Mattax's photo in post 15 is on the money.
The 5 volts to the fuel guage is internal from it's output, if you apply 5v to a and s on the fuel guage the guage should move.

Looks like Chrysler used the same cardboard on the block of all the gauges so A, I and S are meaningless.

On fuel, S is sender, I is 12v from ignition switch, A is 5V output to the other guages and itself.

On the temp guage, S is the 5V in and I is the sender.

On the oil guage (assumption as I have not seen the back of it) S is the 5V in and I is the sender.

As others have pointed out polarity is not an issue on temp and oil. It is on fuel.
 
The fuel guage has an internal jumper from the output post A to the guage so voltage between A and S will cause needle movement.

IMHO +VE to A and -VE to S will get needle movement. Keep voltage below 5v.

The capacitor is for noise suppression and point protection from and in the IVR
 
I = input, for this gauge thats 12 volts, A=altered or adjusted voltage , S=sender or signal.
The 2 post gauges use I and A. This input voltage was altered or adjusted elsewhere.
If you had put 5 or 6 volts at the I post of the fuel gauge, it wouldn't harm anything. That mechanical limiter wouldn't function. Voltage through it to the A post? I never tried/tested. It wouldn't be much.
The solid state regulators need a minimum of 9 volts input to function.
 
A 6 volt high amp lantern battery could cause a crusty gauge to do what it wouldn't do in the car with proper input. 3 volts should get needle movement a tad more than half the range.
 
RedFish said:
A 6 volt high amp lantern battery could cause a crusty gauge to do what it wouldn't do in the car with proper input. 3 volts should get needle movement a tad more than half the range.
Click to expand...
So it is safe to put 3 volt power source directly across the gages with no additional load?
 
Thanks all still on my 1st cup of coffee, so "s" and "i" are +ve, and -ve ? Like I said 1st cup of coffee, and read thru new replies a couple times.
 
You must log in or register to reply here.
-

Back
Top